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AECTP Icing Climatic testing

AECTP 300 Method 311 Icing Compliance Testing

AECTP method 311 testing evaluates the effects icing has on the operational capability of material. As an ISO-17025 accredited environmental compliance test lab, Keystone Compliance realizes the importance of icing compliance testing. Meeting the environmental AECTP 311 testing requirements can be difficult. We understand the challenges and guide companies through the process. 

Keystone’s engineers take a consultative approach throughout the entire test program. We are in constant communication throughout the entire test process. When products do not meet the requirements, we assist with the troubleshooting process. Our proven process helps avoid product launch delays. 

Request a quote to receive testing services tailored to your specific requirements. Have a question about our AECTP laboratory compliance testing capabilities? Contact us to discuss the best course of action.

Summary of AECTP 300 Environmental Climatic Compliance Testing

The AECTP 300 standard is intended to be used in conjunction with four other AECTP test standards (AECTP 100, 200, 400, and 500). Furthermore, the AECTP standard provides advice for preparing environmental test specifications, plans, and procedures.

AECTP 300 evaluates climatic environments. These environments can occur individually or in combination with other climatic or mechanical environments.

The AECTP 300 tests outlined provide exposure to simulated conditions from which a degree of confidence can be established. 

During testing, the configuration used for the selected test should be used within the unit’s life cycle. As a minimum, the following is considered: 

  • In the shipping/storage container or transit case.
  • Protected or unprotected.
  • In its normal operating and thermal configuration.
  • Modified with kits for special applications.

Any of the following will be classified as a failure:

  • A deviation of monitored functional parameter levels beyond acceptable limits.
  • Failure of safety requirements or the development of safety hazards.
  • Failure of specific test item requirements.
  • Changes to the test item that could prevent it from meeting its intended service life or maintenance requirements.

Scope of Method 311 Icing Compliance Testing

AECTP Method 311 icing is conducted to evaluate the effects of icing on material. More specifically, this standard assesses the effects icing has on the operational capability of material.

Additionally, AECTP 311 testing evaluates the effectiveness of de-icing equipment and techniques.

This standard test method is applicable to the following:

  • Material exposed to icing such as produced by freezing rain.
  • For ice accretion from sea splash or spray.

A build-up of ice can occur in four different ways:

  1. From rain, drizzle, or fog falling on material whose surface temperature is at or below freezing.
  2. From sublimation.
  3. From freezing rain falling on material falling on material at or near freezing temperatures.
  4. From sea spray and splash that coats material when the material temperature is below freezing.

Ice formation can block material operation and survival. It can also affect the safety of the operating personnel by creating the following problems:

  • Binding moving parts together
  • Adding weight to radar antennas, aerodynamic control surfaces, helicopter rotors, etc.
  • Increasing footing hazards for personnel
  • Interfering with clearances between moving parts
  • Inducing structural failure
  • Reducing airflow efficiency as in cooling systems or filters
  • Impeding visibility through windshields and optical devices
  • Affecting transmission of electromagnetic radiation
  • Reducing efficiency of aerodynamic lifting and control surfaces

There are two types of ice formations commonly found during testing.

Rime Ice

A white or milky and opaque granular deposit of ice formed by the rapid freezing of supercooled water drops. Rime is generally lighter, softer, and less transparent than glaze ice.

Factors that favor rime formation are:

  • Small drop size
  • Slow accreditation
  • A high degree of supercooling
  • Rapid dissipation of latent heat of fusion

Glaze Ice

Glaze ice is categorized as a coating of ice that is generally clear and smooth. The ice usually contains some air pockets, formed on exposed objects. This is done by the freezing of a firm of supercooled water vapor.

Glaze ice is generally denser, harder, and more transparent than rime ice. Glaze ice occurs when rain or drizzle freezes on objects. Since glaze ice is more difficult to remove, it is structurally a more significant factor and should be the focus of the test.

AECTP 300 Method 311 Icing Testing Procedures

When performing AECTP 311, the droplet size can range from 1.0 to 1.5 mm in diameter. Unless otherwise noted, ice thickness can be one of four options.

  1. 6 mm – light loading
  2. 13 mm – medium loading
  3. 37 mm – heavy ground loading and marine mast loading
  4. 75 mm extremely heavy ground loading and marine deck loading

Before starting the test, all outside surfaces of the unit are cleaned. This will reduce any contamination not during normal operation.

The water used in the spray system is cooled between 0 and 3 C.


First, the test item is placed in the chamber. The temperature is stabilized to roughly 0 C.

Next, a precooled water spray is delivered for one hour. This will allow water to penetrate into the test item.

After, the chamber temperature is adjusted to -10 C. This is maintained for a minimum of four hours to allow the ice to harden. Sometimes, the test program allows for ice removal. The effectiveness of the ice removal techniques is noted.

Lastly, the unit under testing is examined for safety hazards. If appropriate, the unit is operated at a specific low operating temperature of the material.

Expert AECTP 300 Method 311 Icing Testing Laboratory

In addition to AECTP climatic testing, Keystone has a full scope of expertise including solar radiation, humidity, and vibration testing. Our team strives to give our customers more time and energy on product development instead of testing. 

Contact us to see why so many companies work with Keystone each year to achieve their environmental standard test needs.

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